1. Field of the Invention
This invention relates to a method for adjusting the compression stroke allowance of a vertical injection-compression molding machine.
2. Description of the Prior Art
In the molding operation by an injection-compression molding machine, it is important to maintain an allowance for a compression stroke while clamping molds for injection thereinto of a resin. With regard to such a mold clamping method, Japanese Laid-Open Patent Application No. 57-96833 proposes clamp mechanisms as shown in FIGS. 4 and 5 of the present application.
In FIG. 4, indicated at 1 is a fixed die plate, at 2 a movable die plate, at 3 tie bars, at 4 a tie bar mounting block, at 5 a fixed mold, at 6 a movable mold, at 7 a mold clamp cylinder, and at 8 a stopper.
The molds 5 and 6 are clamped by the cylinder 7, driving the movable die plate 2 to the position indicated by solid line. For adjusting the compression stroke allowance .delta., a desired length is measured with a scale and the stopper 8 is fixed at the distance .delta. from the solid line position. Thereafter, the movable die plate 2 is retracted until it abuts against the stopper 8 by operating the mold clamp cylinder 7. In this state, a resin material is injected and filled in the molds 5 and 6.
In the case of the arrangement shown in FIG. 5, a stopper 11, which determines the foremost advanced position of a piston 10, is provided in a hydraulic cylinder 9. In that position, a spacer 12 of a suitable thickness is fixed to the piston 10 of the cylinder 9 through a stopper end 13 to retain a compression stroke allowance .delta..
Thus, the conventional machines require troublesome and inefficient work for adjusting the allowance for the compression stroke, either determining the position of a stopper according to measurement with a scale or determining the position of a stopper end by selecting a spacer of a suitable thickness each time the allowance is to be changed.